The Federal Communications Committee of USA specifies that devices for sensing TV white space should be capable of detecting wireless microphone signals at a received power level −107 dbm. At such a low power level, continuous wave narrowband interference caused by spurious emissions, leakage, intermodulation and the like are quite similar to microphone signals. The inability for most existing detection methods to effectively distinguish between wireless microphone signals and narrowband interferences has led to an excessively high false alarm rate and thus severely limited the utility of sensing-based cognitive transmission in the TV white space spectrum.